using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;

namespace FreeImageAPI
{
    /// <summary>
    /// Provides methods for working with generic bitmap scanlines.
    /// </summary>
    /// <typeparam name="T">Type of the bitmaps' scanlines.</typeparam>
    public sealed class Scanline<T> : MemoryArray<T> where T : struct
    {
        /// <summary>
        /// Initializes a new instance based on the specified FreeImage bitmap.
        /// </summary>
        /// <param name="dib">Handle to a FreeImage bitmap.</param>
        public Scanline(FIBITMAP dib)
            : this(dib, 0)
        {
        }

        /// <summary>
        /// Initializes a new instance based on the specified FreeImage bitmap.
        /// </summary>
        /// <param name="dib">Handle to a FreeImage bitmap.</param>
        /// <param name="scanline">Index of the zero based scanline.</param>
        public Scanline(FIBITMAP dib, int scanline)
            : this(dib, scanline, (int)(typeof(T) == typeof(FI1BIT) ?
                FreeImage.GetBPP(dib) * FreeImage.GetWidth(dib) :
                typeof(T) == typeof(FI4BIT) ?
                FreeImage.GetBPP(dib) * FreeImage.GetWidth(dib) / 4 :
                (FreeImage.GetBPP(dib) * FreeImage.GetWidth(dib)) / (Marshal.SizeOf(typeof(T)) * 8)))
        {
        }

        internal Scanline(FIBITMAP dib, int scanline, int length)
            : base(FreeImage.GetScanLine(dib, scanline), length)
        {
            if (dib.IsNull)
            {
                throw new ArgumentNullException("dib");
            }
            if ((scanline < 0) || (scanline >= FreeImage.GetHeight(dib)))
            {
                throw new ArgumentOutOfRangeException("scanline");
            }
        }
    }
}